Small intestine & Superior Mesenteric Artery

Dr. Nimir, Dr. Safaa

Objectives• Length of jejunum and ileum• Definition of the mesentary• Define the root of the mesentary its length and

extent.• Contents of the mesentary.• Distinction between jejunum and ileum(List the differences between jejunum and ileum)• Superior mesenteric artery and vein• Lymphatic drainage of the jejunum and ileum

Jejunum and Ileum• The jejunum represents the proximal

two-fifths.• It begins at the duodenojejunal flexure.• The ileum represents the distal three-

fifths. It ends at the ileocecal junction.• Together, the jejunum and ileum are 6

to7 m long

Definition• The mesentery is a fan-shaped fold

of peritoneum that attaches the jejunum and ileum to the posterior abdominal wall

The root (origin) of the mesentery The root (origin) of the mesentery is

approximately 15 cm long.It is directed obliquely, inferiorly, and to the right . It extends: from the duodenojejunal junction on the

left side of vertebra L2 to the ileocolic junction .

The root of the mesentery crosses : the ascending and horizontal parts of

the duodenum abdominal aorta IVCright ureter right psoas majorright testicular or ovarian vessels.

Contents Superior mesenteric vessels, The lymph nodes draining the small

gut Autonomic nerve fibres. A variable amount of fat

Jejunum and Ileum

SUPERIOR MESENTERIC ARTERY:- The superior mesenteric artery arises

from the anterior surface of the abdominal aorta approximately 1 cm inferior to the celiac trunk at level L1.

Branches:-Ileocolic arteryRight colic arteryMiddle colic artery12-15 jujenal and ileal branches

• The superior mesenteric vein• The superior mesenteric vein drains

the jejunum and ileum .• It lies anterior and to the right of the

SMA in the root of the root the mesentary .• The SMV ends posterior to the neck of

the pancreas, where it unites with the splenic vein to form the portal vein

Venous DrainagePortal circulation

Lymph Drainage• Lymph from viscera supplied by the the

superior mesenteric artery drain into the superior mesenteric nodes

Mesenteric nodes ( Regional Nodes) ↓ Superior mesenteric nodes Celiac n. cisterna chyli Thoracic Duct